1. Field.
The present invention relates generally to friction clutches and more particularly to improved locking apparatus for securing the fulcrum ring in a selected position of adjustment. In addition the invention includes a positive interlocking drive between a belleville engaging spring and a release sleeve.
2. Prior Art.
In friction clutches, it is known to provide a rotatably adjustable fulcrum ring which is usually mounted on a threaded portion of either a rotatable housing or rotatable pressure plate such that rotation of the fulcrum ring relative to the threaded portion results in axial movement of the fulcrum. As the clutch undergoes changes in rotational speed, the mass of the fulcrum ring tends to cause rotation of the ring relative to the pressure plate and housing which would in turn bring about a change in clutch adjustment unless restrained. The prior art includes various examples of locking devices for the purpose of securing the fulcrum ring in a selected position of adjustment with respect to the pressure plate and housing. Such prior locking devices ordinarily include a tongue like portion which is inserted in a slot portion of the fulcrum ring to prevent rotation of the ring relative to the pressure plate and housing. If dimensional clearance is provided between the tongue and slot, changes in rotary inertia of the ring causes the walls of the slot to hammer on the edges of the tongue which results in undesirable noise, sometimes referred to as "chucking", and may result in destruction of the locking member. On the other hand, if dimensional clearance is not provided between the slot and tongue, it becomes exceeding difficult to reinstall the locking devices after the clutch is installed in a vehicle and readjustment of the clutch has become necessary. It is desirable, therefore, to provide additional improvements in locking devices for the fulcrum ring of a clutch. The present invention is directed to improved locking apparatus for an adjustable fulcrum ring in a friction clutch.
A further problem encountered with clutches according to the prior art arises from relative rotation between a release sleeve and portions of the clutch apply apparatus. Such relative rotation results in wear which when multiplied through the mechanical advantage provided by the operating apparatus results in a significant loss of effective pedal travel.